In order to further accelerate the transformation and upgrading of marine theme parks and promote the high-quality development of the marine tourism industry, code analysis and online text analysis based on online visitor review data from 30 marine theme parks in China were used to conduct a study on visitor perception in marine theme parks. The results are as follows. Parent-child tourism is the main form of tourism in China's marine theme parks, and most tourists have a positive attitude towards the perception of the tourism image of China's marine theme parks, with high satisfaction. In positive emotional reviews, the high-frequency words that appear more frequently are in the categories of emotional experience and tourism attractions, with the highest proportion of high-frequency words in the category of recommendation degree in emotional experience, and the relatively high proportion of high-frequency words in the category of featured venues and marine organisms in tourism attractions.In negative emotional reviews, the highest frequency of high-frequency words is in the category of tourism attractions, followed by emotional experience and management services. Among them, tourism attractions, tourism costs, public security level, and service quality are the main reasons for negative emotions among tourists.